The stone cathedrals of Europe are architectural masterpieces that have withstood the test of time and the ravages of war. But one has to wonder: Did medieval architects account for the corrosive power of pee?

Officials charged with the maintenance of a historic Ulm Minster church tower in Germany complain that local revelers are damaging the integrity of the building by urinating on the structure’s stone walls, CNN reported Wednesday.

Maintenance officials said the tower’s stone base, a target of the after-hours crowds, is being eroded by salt and acids in the urine, CNN reported, citing Südwest Presse, a daily newspaper in Ulm.

Persons who urinate in public, or “wildpinklers,” as they’re nicknamed in German, are such a problem in Ulm that the city has recently doubled its fine for the act to 100 euros, CNN said.